Chuncks regenerating which deletes anything built there

I logged in to a creative non-flat world where i have been building stuff and all of the sudden new chuncks started appearing and replacing things that i have previously built. Pretty destructive bug to say the least.
How to recreate:
1. Log in to a world where you have already made a great amount of changes to the enviorment.
2. Watch as your creations get destroyed by new chuncks generating.